The Zenit (Zenith) rocket was the last, and most advanced, space
launch vehicle developed by the former Soviet Union. Although it began life as a military
satellite launcher, its primary use in recent years has been to boost commercial
satellites into space for the multi-national Sea Launch venture.

Zenit development was begun by Dnepropetrovsk, Urkraine-based NPO
Yuzhnoe during the 1970s as an effort to replace ICBM-based boosters with a purpose-built
space launcher. Early plans called for a modular series of light, medium, and heavy-lift
vehicles, but only the 11K77 medium version won approval. On March 16, 1976, the Central
Committee of the Soviet Union officially approved development of the 11K77 two-stage
Zenit-2, a rocket capable of boosting 13.7 metric tons into low earth orbit (LEO) from
Baikonur, as a replacement for the Tsyklon booster then in use. Subsequently, Zenit-2 won
the job of launching the USSR's new Tselina-2 electronic intelligence satellites while the
Zenit-2 first stage was selected to serve as a strap-on booster for the Energia heavy-lift
launcher. Initial planning called for the first Zenit-2 launch to occur in 1982.

Development of Zenit's powerful
staged-combustion cycle first stage engine by the Glushko design bureau (later called
Energomash) soon ran into trouble, however. The four-chamber, single-turbopump
kerosene/liquid oxygen (LOX) engine, identified as RD-170 for Energia and RD-171 for
Zenit-2, suffered a series of test failures during 1981-83 that threatened both programs.
The development challenge was daunting. RD-170/RD-171 was the most powerful liquid
propellant rocket engine ever developed, producing more thrust than the Saturn V F-1 (806
tons versus 789 tons) and operating at higher chamber pressures than NASA's Space Shuttle
Main Engine (245 bar versus 204 bar). Eventually, Glushko was able to qualify the powerful
engine for flight.

The rocket's first stage consisted of an engine compartment
topped by a kerosene tank and, on top of both, a LOX tank. The tanks shared a common
bulkhead. All four RD-171 chambers gimballed to provide three-axis control.

The second stage used a single fixed RD-0120 main engine
augmented by the four gimballed thrust chambers of an RD-8 vernier engine. A toriodial
kerosene tank wrapped around the RD-0120 engine. A separate cylindrical LOX tank was
positioned above the engine section. The launch vehicle control system was mounted atop
the second stage.

A new launch
complex, named Area 45, was constructed on Baikonur's eastern flank. The pad site allowed
"automatic" launch processing, with the horizontally integrated launch vehicle
transported to and erected on the "launch starter" pad only 90 minutes before
liftoff. The process included automatic connection of propellant, power, and data lines.
Area 45 included two pads. The "left" pad hosted all initial launches and is
still in use. The "right" pad entered service in May 1990, but it was destroyed
by an on-pad explosion during its second use in October of that year.

On April 13, 1985, the first 57 meter tall, 460 ton Zenit-2
lifted off from the "left" pad at Baikonur Area 45 with a dummy payload
representing a Tselina-2 satellite. The first stage performed well, but problems with the
second stage propellant controller caused the RD-0120 second stage engine to run out of
fuel and shut down a few seconds early, leaving the vehicle short of orbital velocity.
Another second stage problem doomed the second launch on June 21, 1985. Finally, on
October 22, 1985, the third Zenit-2 successfully reached orbit with a dummy payload that
was announced as Kosmos-1697. Eight more Zenit-2 launches were performed before the
vehicle was declared operational at the end of 1987.

Within a few years, however, the collapse of the Soviet Union,
the end of the Energia/Buran program, and the technical challenges offered by the new
rocket contributed to a series of failures. On October 4, 1990, the 15th Zenit-2 failed
five seconds after the liftoff from Area 45 "right" launch complex. The 460 ton
rocket fell back through the pad into the flame trench and exploded, obliterating the
massive concrete launch pad. The next two Zenit-2 launches, in 1990 and early 1991, fell
short of orbit when their second stages failed. After a series of successes, another
Zenit-2 failed 48 seconds after liftoff on May 20, 1997.

Zenit returned to service with two successful government launches
in 1998, but the rocket suffered an embarrassing failure on September 9, 1998. During its
first international commercial satellite launch attempt with 12 Globalstar satellites, the
rocket suffered a control system failure during the second stage burn. Globalstar had
planned to buy multiple Zenit-2 launches, but after the failure the company switched to
Boeing Delta II and Starsem Soyuz. The failure, combined with Russia's gradual ending of
Zenit-2 military launches, dealt a serious blow to the rocket. Only four Zenit-2 launches
occurred between 1999 and 2001, and none took place in 2002.

Zenit managed an
unlikely rebirth, however. During the early 1990s, several companies began studying the
creation of a three-stage "Zenit-3" to launch commercial satellites into
geosynchronous transfer orbit (GTO) from a floating launch platform. Payload mass could be
increased by launching from the equator, where the Earth's rotation provides more velocity
to assist the launcher. Russia's RKK Energia offered its Blok DM as an upper stage, USA's
Boeing its payload integration and western marketing skills, Norway's Anglo-Norwegian
Kverner Group the floating launch platform and command ship, and SDO Yuzhnoye/PO Yuzhmash
the two-stage Zenit, launcher equipment, and launch operations. The four companies
officially formed Sea Launch in 1995 with 25%, 40%, 20%, and 15% shares, respectfully.
Plans called for Sea Launch operations to be based in Long Beach, California, near several
major satellite manufacturers.

For Sea Launch, Zenit's first stage was strengthened,
the second stage engine thrust was increased, more propellants were loaded, and
electronics were upgraded. The improved rocket, named Zenit-3SL, was topped by the Blok
DMSL third stage and an enlarged payload fairing. Initially rated to handle 5.25 metric
ton payloads to GTO, Zenit-3SL's payload capacity soon grew to 6 tons.

Hughes signed on as the first Sea Launch customer in 1995, adding
three orders in 1996. Space Systems/Loral ordered five launches in 1996.

In late 1996, the "Sea Launch Commander" was launched
from the Kyaerner shipyard in Scotland. Both "Commander" and launch platform
"Odyssey" sailed to Russia in 1997 for outfitting. On June 12, 1998,
"Commander" departed St. Petersburg, Russia for Long Beach, carrying the first
two Sea Launch vehicles. Eight days later "Odyssey" left Russia for Long Beach,
making an epic journey through the Dardenelles Straight.

After weathering a 1998 suspension of work
order from the U.S. government due to technology transfer concerns, Sea Launch Zenit
successfully performed its first launch with a dummy payload on March 27, 1999. On October
9, 1999, the second Zenit 3SL successfully boosted Direct TV 1-R into GTO.

On March 12, 2000, Sea Launch suffered its first launch failure.
The ICO F-1 communications satellite was lost after the rocket's second stage shut down 80
seconds early. A control pressure valve commanding error in the pre-launch ground sequence
software was responsible. The improper valve setting caused control of the second stage
RD-8 vernier engines to be lost after some time passed, so that the stage tumbled out of
control. The rocket's control system automatically shut down the RD-0120 engine when it
lost control authority.

Sea Launch recovered with eight consecutive successful launches,
but the 14th flight failed in mid-2004 when the DMSL stage shut down 54 sec early due a
suspected loose electrical connection. The Apstar 5 payload was left in a transfer orbit
with an apogee 14,000 km lower than planned, but the satellite was subsequently able to
use its own fuel to reach the planned geosynchronous orbit.

Zenit 3SL
then reeled off nine consecutive successes, including five in 2006. Spaceway 1,
orbited during that string, was, at 6.1 tonnes, the heaviest commercial GTO payload
launched up to that time. But the run ended emphatically on January 30, 2007 when a
Sea Launch Zenit with SES New Sky's NSS-8 satellite exploded in a huge fireball at
liftoff. The failure, caused by the ingestion of a metal object by the RD-171M
main engine's LOX turbopump, knocked off and sank Odyssey's 250 tonne exhaust deflector
and damaged other parts of the platform and its launch equipment. While Sea Launch
scrambled to repair Odyssey, several payloads drifted away to Ariane or Proton.

Sea Launch was ready to return to flight during the final weeks
of 2007, but poor weather conditions at the launch site forced Odyssey to return to port.
Zenit 3SL finally returned to service on January 15, 2008 with the successful launch
of Thuraya-3.

While Sea
Launch battled its way back from the 2007 failure, a Zenit renaissance was being planned
for Baikonur, where "Land Launch" Zenit flights were scheduled. Zenit 2
SLB and Zenit 3 SLB variants would carry commercial payloads from Baikonur's remaining
45/1 pad. On June 29, 2007, a Zenit 2M, equipped with the RD-171M and upgraded
digital flight control computer that the new Land Launch Zenit's would use, flew
successfully from Baikonur.

The first Zenit 3 SLB, a two-stage Zenit topped by an RSC Energia
Blok DM-SLB third stage, arrived at Baikonur for pre launch processing in late 2007.
On April 28, 2008, the rocket carried Amos 3, an Israeli communication satellite, into
near geosynchronous orbit from Area 45, Pad 1.

Sea Launch Bankruptcy

On June 24, 2009, about three months and 10 years after it
performed its first demonstration space launch from a platform floating in the Pacific
Ocean, Sea Launch Company filed for Chapter 11 bankruptcy court protection. The unique
international consortium, owned by Boeing (40 %), Russia's RSC-Energia (25 %), Aker ASA of
Oslo, Norway (20 %), and Ukraine's SDO Yuzhnoye/PO Yuzhmash (15%) listed assets of
$0.1-0.5 billion and liabilities of $0.5-$1 billion. Boeing said that it might have
to charge as much as $0.513 billion against earnings as a result of the bankruptcy. Sea
Launch reportedly owed Boeing $0.978 billion in loans, trade debt, and partner
liabilities.

The Long Beach, California-based company said that it planned to consider selling one or
more of its divisions, but that it intended to use cash on hand to meet operating expenses
and that it intended to continue to operate after the filing. Sea Launch owned a
stake in Land Launch, which might or might not be considered a "division".

It was the first time that a major, established launch services
company had declared bankruptcy. Other companies, like Kistler, failed prior to
establishing service. For that reason, it was difficult to predict whether Sea
Launch would emerge as a continuing business. The partners, especially Boeing, were
likely in position to decide whether or not the business continued.

At the time of the filing, Sea Launch reportedly had a 10 launch backlog, including eight
Sea Launch and two Land Launch missions from Baikonur, Kazakstahn. Two to three launches
were planned for 2009, but Sea Launch had recently lost three payloads to Russian
competitor International Launch Services. The switches were caused by program delays
following a 2007 Zenit 3SL launch failure, by the 2008 financial crises, and by delayed
Zenit 3SL/Blok DMSL deliveries.

Zenit
3F

On January 20, 2011, the first Zenit 3F (or Zenit 3SLBF) was used
to orbit Russia's first Electro-L weather satellite from Baikonur. Zenit 3F used an
upgraded hypergolic Fregat SB upper stage in place of Energia's cryogenic Blok DMSLB
stage. Fregat SB added drop tanks to the previously-flown Fregat stage.

Sea Launch Zenit Fails (Updated Febraury 2, 2013)

A Zenit 3SL/Blok DMSL failed shortly after launch from
Sea Launch Odyssey launch platform in the equatorial Pacific Ocean on February 1, 2013,
destroying the rocket and its Intelsat 27 satellite payload. It was the fourth Sea
Launch failure in 35 flights, breaking a string of 10 consecutive successes spanning six
years.

Liftoff occurred at 06:56 UTC. The rocket rose for
about 23 seconds before appearing to veer just before its RD-171M main engine suddenly cut
out, darkening the scene. Webcast video then showed a brief flash of light about 58
seconds after liftoff, possibly indicating the time of impact with the ocean surface.
No injuries or damage to Sea Launch floating systems were reported.

The behavior was consistent with an emergency cut off
command given to the main engine, a range safety procedure used with Ukrainian and Russian
rockets that have flown out of control.

Sea Launch later announced that it had lost telemetry
signals about 40 seconds after liftoff, and that it would conduct an investigation to
determine the cause. Russian news services reported that the flight had been
terminated after drifting from its planned flight path. RD-171M engine manufacturer
NPO Energomash director Vladimir Solntsev stated that the engine had worked nominally and
that it was not involved in the failure.

Failure Review Oversight Board

On February 2, Sea Launch announced that 11.4 seconds into flight, "the Zenit flight
control system detected an exceedance of a pre-programmed roll limit" indicating a
loss of vehicle control, triggering the on-board thrust termination sequence. The
sequence terminated the RD-171M main engine thrust 20 seconds into the flight. The
rocket and its payload impacted the Pacific Ocean surface about 4 km from the Odyssey
Launch Platform.

Sea Launch announced that a Failure Review Oversight
Board (FROB) would investigate the failure, focusing on systems involved in the thrust
vector control of the first stage engine.

Intelsat 27 was a 6.215 tonne satellite built by Boeing
Satellite Services. It would have been inserted into geosynchronous transfer orbit.

Zenit 3SL consists of a two-stage rocket Zenit 2S
developed by SDO Yuzhnoye of Ukraine, topped by a Blok DMSL upper stage manufactured by
Russia's RSC Energia, the majority owner of Sea Launch itself. Russia's NPO
Energomash provides engines for the first two stages.

It was the 80th Zenit series launch since the family
entered service in 1985, and the 13 failure.

Sea Launch had conducted four successful missions since
emerging from its 2009 bankruptcy.

Sea
Launch Returns

Sea Launch returned to the orbital launch scene on May
26, 2014 for the first time since a February 2013 launch failure. The company's Ukrainian
built two-stage Zenit 3SL rocket, topped by a Russian-built Blok DMSL third stage, boosted
Eutelsat 3B into geosynchronous transfer orbit after lifting off from Odyssey Launch
Platform floating on the Pacific Ocean near the equator at 154 deg. West Longitude.

Zenit 3SL/DMSL lifted off at 21:10 UTC on 740 tonnes of liftoff thrust from its
four-chamber RD-171M Russian engine. The first two stages fired in sequence during the
first 8.5 minutes of the mission. Blok DMSL then performed two burns separated by a 30
minute long coast to insert the 5.967 tonne satellite into a 385 x 35,686 km x 0 deg
transfer orbit. The first burn lasted 4 minutes 40 seconds. The second burn was 6 minutes
57 seconds long.

Airbus Defence and Space built Eutelsat 3B, which was based on the Eurostar 3000 platform.
The satellite was equipped with up to 51 C, Ku, and Ka band transponders. it will serve
Africa, the Middle East, Central Asia and South America.

No more Sea Launch missions are currently planned until 2016. Following its bankruptcy
reorganization, Sea Launch became 95% Russian-owned. Its next payloads are Russian
built satellites for Russian users. Accordingly, Russia has been contemplating moving Sea
Launch operations from Long Beach, California to an eastern Russian port.

Sea Launch Scales Back

On August 22, 2014, Sea Launch announced that it would
lay off employees at both its Nyon, Switzerland headquarters and at its Energia
Logistics Long Beach, California Home Port due to a multi-year gap in manifested
launches. The company said that it would also take its Launch Commander and Odyssey
vessels out of service to save money. Sea Launch said that it would "retain key
personnel across all corporate and technical functions" to allow the company to
restart itself after one or two years.